epoch

epoch, unit of geologic time that is a subdivision of a period. The Pleistocene and Holocene epochs, for example, are divisions of the Quaternary period. Epoch is also used to describe a short length of geologic time during a special occurrence, such as the glacial epoch. See geology; Geologic Timescale (table).

or glacial age

Any geologic period during which thick ice sheets cover vast areas of land. Such periods of large-scale glaciation may last several million years and drastically reshape surface features of entire continents. A number of major ice ages have occurred throughout the Earth's history; the most recent periods were during the Pleistocene Epoch (1.8 million–10,000 years ago).

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Unit of geologic time during which a rock series is deposited. It is a subdivision of a geologic period. Additional distinctions can be made by adding relative time terms, such as early, middle, and late. The use of the term is usually restricted to divisions of the Tertiary and Quaternary periods.

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Periodization

In periodization, epoch can refer to:

• Epoch (reference date) - A defining moment in the beginning of, or characteristic of, a distinctive historical period or era.
• On the geologic time scale, a span of time smaller than a "period" and larger than an "age".
• A phase in the development of the universe with distinctive properties during the the Big Bang.
• Epoch (astronomy) - a precise moment in time for which celestial coordinates or orbital elements are specified by international agreement, usually periodically reset to centennial and half-century dates. All other orbits calculations near or after the astronomical epoch are based on the epoch date.
• Many computer operating systems maintain system time based on some starting time called the epoch. For example, Unix and POSIX systems count time as seconds since January 1 1970. See Unix time.

Proper noun

• Epoch (magazine), the literary magazine of Cornell University.
• Ha-Tsefirah (lit. Epoch), a Hebrew language newspaper published in 1862 and 1874-1931.
• Epoch (film), a science fiction film directed by Matt Codd
• Epoch Game Pocket Computer, an early hand-held game console
• Epoch Co., the maker of the above and other computer games
• Epoch (Chrono Trigger), a flying time machine in role-playing game Chrono Trigger
• Epoch (DC Comics), a supervillain also known as the Lord of Time
• Epoch (Marvel Comics), a cosmic entity in the Marvel Comics universe.
• Epoch Hunter, a boss in World of Warcraft's Caverns of Time; Old Hillsbrad Foothills.
• The Epoch Times, a privately owned Falun Gong-linked newspaper
• Epoch Javascript Calendar is an open source, GPL calendar component for use in web pages written in JavaScript.
• Epoch operating system was a European research project in the 1990s to build an operating system based on the ChorusOS operating system kernel.

Other

• A step in the training process of an artificial neural network